Method and apparatus for connecting a micro-actuator to driver arm suspension

ABSTRACT

A system and method for connecting an actuator to a suspension element is disclosed. The actuator is electrically coupled using a silver paste. The silver paste is further covered by a coating application to provide structural support. A step, attached to either the actuator base or the suspension tongue, provides further structural support and maintains a gap between the actuator and the suspension element.

BACKGROUND INFORMATION

The present invention relates to magnetic hard disk drives. Morespecifically, the present invention relates to a method of connectingthe micro-actuator to the driver arm suspension.

In the art today, different methods are utilized to improve recordingdensity of hard disk drives. FIG. 1 provides an illustration of atypical drive arm configured to read from and write to a magnetic harddisk. Typically, voice-coil motors (VCM) 102 are used for controlling ahard drive's arm 104 motion across a magnetic hard disk 106. Because ofthe inherent tolerance (dynamic play) that exists in the placement of arecording head 108 by a VCM 102 alone, micro-actuators 110 are now beingutilized to ‘fine-tune’ head 108 placement. A VCM 102 is utilized forcourse adjustment and the micro-actuator then corrects the placement ona much smaller scale to compensate for the VCM's 102 (with the arm 104)tolerance. This enables a smaller recordable track width, increasing the‘tracks per inch’ (TPI) value of the hard drive (increased drivedensity).

FIG. 2 provides an illustration of a micro-actuator as used in the art.Typically, a slider 202 (containing a read/write magnetic head; notshown) is utilized for maintaining a prescribed flying height above thedisk surface 106 (See FIG. 1). Micro-actuators may have flexible beams204 connecting a support device 206 to a slider containment unit 208enabling slider 202 motion independent of the drive arm 104 (See FIG.1). An electromagnetic assembly or an electromagnetic/ferromagneticassembly (not shown) may be utilized to provide minute adjustments inorientation/location of the slider/head 202 with respect to the arm 104(See FIG. 1).

The physical and electrical coupling of a hard disk micro-actuator andmagnetic head to a drive arm suspension can be difficult due to theenvironment within which it must operate. Using silver paste (highmercury-content epoxy) for physical/electrical attachment has drawbacksdue to the viscous nature of epoxy under changing temperature andhumidity. Under certain temperature and humidity conditions, the epoxycan deform, affecting the position of the slider and micro-actuator inrelation to the suspension arm. Additionally, silver ions or silveratoms in the silver paste may begin to migrate from the epoxy to themicro-actuator, affecting the performance of the micro-actuator. Whileother options for bonding the actuator to the suspension arm exist, suchas gold ball bonding (GBB) and solder bump bonding (SBB), the rigidityof these options can lead to greater damage. In particular, the thinnessof the piezoelectric transducer (PZT) surface layer of themicro-actuator can reduce the peel strength between the PZT layer andthe bonding pad, causing the connection to crack and create anelectrical short between the two. It is therefore desirable to supportthe micro-actuator and connect it to the suspension arm using a methodthat can create strong a connection without the risks of deformation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides an illustration of a drive arm configured to read fromand write to a magnetic hard disk as used in the art.

FIG. 2 provides an illustration of a micro-actuator as used in the art.

FIG. 3 describes a hard disk drive head gimbal assembly (HGA) with a‘U’-shaped micro-actuator according to an embodiment of the presentinvention.

FIG. 4 provides an illustration of a U shape micro-actuator designaccording to an embodiment of the present invention.

FIG. 5 provides an illustration of the configuration of the coatingapplication according to an embodiment of the present invention.

FIG. 6 provides an illustration of a step suspension according to anembodiment of the present invention.

FIG. 7 provides an illustration of step actuator according to anembodiment of the present invention.

DETAILED DESCRIPTION

A system and method for connecting an actuator to a suspension elementis disclosed. The actuator is electrically coupled using a silver paste.The silver paste is further covered by a coating application to providestructural support. A step, attached to either the actuator base or thesuspension tongue, provides further structural support and maintains agap between the actuator and the suspension element.

Illustrated in an upside-down orientation, FIG. 3 describes oneembodiment of a hard disk drive head gimbal assembly (HGA) with a‘U’-shaped micro-actuator. In this embodiment, a slider 302 is bonded attwo points 304 to a ‘U’-shaped micro-actuator 306. In a furtherembodiment, the ‘U’-shaped micro-actuator has a piezoelectric LeadZirconate Titanate (PZT) beam (arm) 308 on each side of a ceramicsupport frame (actuator base) 310. The micro-actuator 306 is coupled toa suspension 312.

FIG. 4 illustrates one embodiment of the ‘U’shaped micro-actuator 306. Asupport frame 310 supports two piezoelectric Lead Zirconate Titanate(PZT) beams 308. In one embodiment, the support frame is ceramic. The‘U’ shaped micro-actuator 306 is connected to the slider element 302. Inone embodiment, the micro-actuator may be a piezoelectricmicro-actuator, an electromagnetic micro-actuator, an electrostaticmicro-actuator, a capacitive micro-actuator, a fluidic micro-actuator,or a thermal micro-actuator.

FIG. 5 illustrates the coupling of the ‘U’ shaped micro-actuator 306 tothe suspension element 312. In one embodiment, the ‘U’ shapedmicro-actuator 306 is electrically coupled 502 to the suspension bondingpads 504 using a silver epoxy paste or resin. In a further embodiment,the slider 302 is electrically coupled 506 to the suspension bondingpads 508 using a silver epoxy paste or resin. In one embodiment, acoating application 510 covering the electric couplings for themicro-actuator 502 and the slider 506 provides physical support forthese electric couplings. In particular, the coating applicationprovides physical support for these electric couplings for the actuatorelement that can have movement independent of the movement of the HGA.In one embodiment, the coating application has a high glass transitiontemperature (Tg) (e.g., Tg>120 degree Celsius), the temperature at whichglassy solids transition to more flexible rubbery solids. In a furtherembodiment, the coating application has a high Young's modulus (E)(e.g., E>0.6 G Pa), the measure of the stiffness of a material. In oneembodiment, the coating application is an epoxy or a resin. The epoxycoating application can contain a filler material, such as metal, glassor a fiber material. The coating application protects the electriccoupling from deformations caused by changes in humidity andtemperature, as well as physical strain over time. The coatingapplication can also prevent the migration of silver ions or atoms fromthe electric coupling into the electric layer of the PZT of themicro-actuator.

In a further embodiment of the present invention, a step configurationis implemented to further support the micro-actuator. The stepconfiguration further reduces the amount of contact between the sliderand the suspension during movement of the actuator. In one embodiment,the step configuration is implemented using a metal step 602 in thesuspension tongue 312, as shown in FIG. 6. In one embodiment, the step602 is molded into the suspension tongue 312 at formation. In analternate embodiment, a separate step piece 602 is coupled to thesuspension tongue 312 before coupling the micro-actuator 306 to thesuspension element 312. In one embodiment, the material for the step 602is made of polyester, polyethylene, polymer, or ceramic. In a furtherembodiment, the step 602 is coupled to the suspension tongue 312 byepoxy, resin, anisotropic conductor film, or anisotropic conductiveadhesive.

In one embodiment, the base of the micro-actuator 306 is thickened tocreate a step 702, as shown in FIG. 7. The base step 702 of themicro-actuator 306 separates the micro-actuator 306 from the suspension312 and maintains a parallel gap even during changes of temperature andhumidity. In an alternate embodiment, the step 702 is created byattaching a separate step plate to the base of the micro-actuator 306.In one embodiment, the step configuration includes a first step elementcoupled to the micro-actuator and a second step element coupled to thesuspension element. In an alternate embodiment, the step configurationincludes a first step element created by thickening the base of themicro-actuator and a second step element is molded into the suspensiontongue. In a further embodiment, the step 602 is coupled to themicro-actuator element 312 by epoxy, resin, anisotropic conductor film,or anisotropic conductive adhesive.

Although several embodiments are specifically illustrated and describedherein, it will be appreciated that modifications and variations of thepresent invention are covered by the above teachings and within thepurview of the appended claims without departing from the spirit andintended scope of the invention.

1-33. (canceled)
 34. A method, comprising: coupling an actuator elementto a suspension element using at least one application site of a bondingagent; and covering the bonding agent with a coating application. 35.The method of claim 34, further comprising: coupling a magnetic headelement to the suspension element using at least one application site ofthe bonding agent; and covering the bonding agent with the coatingapplication.
 36. The method of claim 34, wherein the actuator element isa micro-actuator.
 37. The method of claim 36, wherein the micro-actuatoris selected from a group consisting of a piezoelectric micro-actuator,an electromagnetic micro-actuator, an electrostatic micro-actuator, acapacitive micro-actuator, a fluidic micro-actuator, or a thermalmicro-actuator.
 38. The method of claim 34, wherein the bonding agent isa silver paste.
 39. The method of claim 34, wherein the coatingapplication has a glass transition temperature greater than 120 degreesCelsius.
 40. The method of claim 34, wherein the coating application hasa Young's modulus greater than 0.6 G Pa.
 41. The method of claim 34,wherein the coating application is an epoxy agent.
 42. The method ofclaim 41, wherein the epoxy agent contains a filler ingredient.
 43. Themethod of claim 42, wherein the filler ingredient is selected from agroup consisting of metal, glass, or a fiber material.
 44. The method ofclaim 34, further comprising maintaining a parallel spatial relationshipbetween the actuator element and the suspension element using a firststep element.
 45. The method of claim 44, further comprising creatingthe first step element by thickening a portion of the actuator element.46. The method of claim 45, further comprising molding a second stepelement into the suspension element.
 47. The method of claim 44, furthercomprising coupling the first step element to a portion of the actuatorelement.
 48. The method of claim 47, further comprising coupling asecond step element to a portion of the suspension element.
 49. Themethod of claim 44, further comprising molding the first step elementinto the suspension element.
 50. The method of claim 44, furthercomprising coupling the first step element to a portion of thesuspension element.
 51. The method of claim 44, further comprisingcoupling the first step element to a portion of the suspension elementusing one of a group of materials comprising epoxy, resin, anisotropicconductive film, and anisotropic conductive adhesive.
 52. The method ofclaim 44, further comprising coupling the first step element to aportion of the micro-actuator element using one of a group of materialscomprising epoxy, resin, anisotropic conductive film, and anisotropicconductive adhesive.